modulation

modulation, in music, shift in the key center of a composition. For its accomplishment use is made of the fact that each chord figures in the harmonic relationships of several keys. In modulating from one key to another, a chord that is common to both keys is used as a pivot chord. If there is no chord common to the two keys, a passage may move through several keys before the desired modulation has been effected. Modulation is commonly employed as a means of achieving variety in a composition and has been in use since the late 15th cent.

See C. Zöller, The Art of Modulation (1930); M. Reger, On the Theory of Modulation (tr. 1948).